Frankly, MR5 still majorly affects Yuya and Rush duel chars.Well of course the extra monster zone is there, they're using modern rules.
He can't spam it anyway, it's once per turn so it's not going to affect him that much.
Unless you're referring to him not having the pendulum zones/extra spell and trap zones which again, is really not going to affect him that much.
Rule 5, they're using rule 5 okay, it basically doesn't affect anybody in any major way so it's the fairest for everyone involved.
Yuya playstyle relies on mass pendulum summoning. And since pendulum summoning from ED will go to Extra deck zone, it will affects his strat no matter what. He can still work on it since he does have other dimensional dragon and their evolutions, but he won't be at 100% capacity.
The lost of action card also hurts him somewhat (later Arc V duels have all the duelists somehow overly relies on them)
Rush Duel chars are affected the worst since Rush duel deck doesn't have searchers nor negation. And rush duel decks main strat is usually mass summoning since their 4* below have low atk, only like 1600 atk and below (with most of their main cards effect benefits greatly if more monsters are in GY).
Limiting them to once per turn summoning will just cripple them.
With that in mind, I think Yusaku has the best shot since his deck seems to be balanced compared to others (discounting magic interference like Zexal Yuma of course)
Honestly, unless we are using Rush Duel format, Rush Duel chars should be excluded.